Same geometry as the aluminium Margin, cut in black ebonite. Hard rubber is a warmer material than anodised aluminium and it takes the temperature of the hand within a minute, which makes a real difference over a long sitting. It is also softer, so the barrel will mark if you drop it on a hard floor, and it will go faintly brown if you leave it in sunlight for a season.
The ebonite version runs 11 g filled and the section is turned 0.3 mm larger than the aluminium at 8.7 mm, because hard rubber needs a slightly thicker wall. Same No. 5 fine nib at 0.45 mm, same slim converter.
We turn these in batches of forty and the surface is finished on a cloth wheel rather than lacquered, so the sheen is low and will deepen with handling. A twice-yearly wipe with a waxed chamois is all the care it needs.
